The invention relates to a method for producing a multi-layer carbon brush consisting of at least two first electrically conductive functional layers made of carbon material and at least one insulating layer made of electrically insulating material, running between successive first functional layers.
A multi-layer carbon brush of the aforementioned type is described in DE 199 13 599 A1.
Multi-layer carbon brushes, which consist of carbon bars and insulating layers extending between them, are frequently used for smaller reversible motors such as those found in washing machines. The insulating layer can consist of a film, an insulating adhesive, synthetic resin or one or more powder resins. Due to the higher transverse resistance the current flowing between the two disks of a commutator covered by the carbon brush is reduced, thus improving commutation.
The familiar multi-layer carbon brushes of the type described above are generally produced by aligning initially heat-treated carbon plates with each other in such a manner that allows a film to be inserted between them. The products are then layers together. This method can thereby allow one zone to have a higher copper content than the other.
As described in DE 44 30 745 a carbon brush referred to as a multi-layer sliding contact is comprised of layers each consisting of a conductive powder. To produce the multi-layer sliding contact, two conductive powders are simultaneously poured into a mold in which a heat treatment process is performed following compression. Not only does this method allow the formation of layers through the simultaneous addition of powder to a mold, but it also facilitates the formation of additional layers through the successive placement of electrically conductive powder into the mold.
DE-C-835 428 describes a highly-polished hard coal molded body as an applied arts object and a method for its production. To accomplish this, carbon is added to a mold, pressed, and then pre-sintered before being machined in order to coat or impregnate the body with oil-containing pastes prior to final sintering.
DE-C-636 540 describes a method for producing multi-layer carbon brushes. Finished carbon layers are first smoothed. Tescous resin with an insulating material is then placed between the two finished carbon layers. The carbon layers are then clamped into a special pressing tool to facilitate drying in a furnace.
A method for producing a laminated material made of carbon is described in DE 33 07 090 A1. To achieve the desired end product, films made of thermoplastic resin are placed through pressing and heat-treatment between carbon layers such as carbon felt layers that can be stacked on top of each other, and the stack is then subjected to the desired pressure and temperature levels.
DE 199 02 938 A1 relates to a carbon brush that is composed of sections having different material compositions. In this case, the carbon brush is produced through a pressing process.
A method for producing a laminated material made of carbon is disclosed in DE 33 07 090 A1. To achieve the desired end product, films made of thermoplastic resin may be arranged by means of pressing and heat-treating between carbon layers such as carbon felt layers that can be stacked on top of each other, and the stack is then subjected to the desired pressure and temperature levels.
DE 199 02 938 A1 relates to a carbon brush that is composed of sections having different material compositions. In this case, the carbon brush is produced through a pressing process.
Vrom EP 1 128 496 A1 we know of a starter carbon brush that consists of a first layer made of a material with low resistance and a peripheral layer made of a material with high resistance, which extending from the running surface of the carbon brush ends at a distance to the opposing rear surface. The first and second layers are produced simultaneously in one mold by filling powder into said mold and then performing a pressing step before finally sintering them.